Prof Grubin replied: “That’s not unusual. It was a developing illness and did not become a big problem until these offences took place.”

The slayings happened on February 1, at the £500,000, five-bedroomed home on Front Street, Benton, North Tyneside, where Patterson lived with his dad and gran.

Patterson was well-behaved as a child, but after he started doing art at college and began misusing alcohol and drugs, his attitude towards his family deteriorated and he became aggressive and threatening.

He had no previous convictions, but police had been called out to the family home a number of times by Ray and Clara after reports he was shouting and banging on doors and windows.

In March 2008, Patterson called police saying his dad had fallen, but the call handler heard a male voice in the background saying he had been pushed.

In April 2009, Patterson was arrested for breach of the peace, but his gran and dad refused to provide statements.

In the same year, Patterson’s mother called police saying he had pinned her to the bed and shouted abuse and threats towards her.

In 2009, his uncle Ian Patterson came to Newcastle to confront Patterson over threats he had made to his dad and gran.

Patterson started taking anti-depressants and moved to London to study in 2009.

He had returned home for Christmas last year, and by February, there was another incident involving police. He called an ambulance while suffering alcohol withdrawal, but paramedics had to call police after he started causing trouble.

Four days later, around 6.20pm on February 11, Patterson was spotted pacing up and down Front Street, near his home, in an agitated and erratic manner.

He was shouting “Where are those noises coming from?” to a passer-by and directed the same question at a set of traffic lights.

Patterson was also spotted near Four Lane Ends Metro station, where he was distressed and again asking people where the noises and voices were coming from.

Around 9pm, he went into The Black Bull pub, near his home, and grabbed a customer’s pint from the bar and took it outside. He came back into the pub, but was escorted out and ran into the road, where he was hit by a car.

He ran off and when the concerned taxi driver followed him, he was punched by Patterson.

Police arrived on the scene and found the bodies of Ray and Clara inside the house.